1. Field of the Invention
The Tensioned Inflatable Cover Module relates to inflatable buildings and in particular to systems for regulating the flow of fluids and radiation into enclosed spaces as provided, for example, in greenhouses and shelters.
2. Description of the Prior Art
Inflatable buildings have been used extensively in the greenhouse and leisure industries where the relatively low weight, cost and ease of installation are major advantages over more rigid structures built of glass or composite materials. The purpose of these installations has been primarily the provision of more or less controlled environments for plant growth or human activities; an increasingly popular benefit of these microclimate zones has been public enjoyment as provided in garden centers, botanical gardens and sports complexes. With the unabating current deforestation worldwide and the consequent environment degradation, these oasis of life may become increasingly important and perhaps even essential to our continued survival on this Earth. Looking ahead, the initial establishment of human settlements on distant planets, currently focused on Mars, is likely to be dependent on the provision of pockets of controlled environment within the inhospitable alien atmospheres. Among inflatable buildings, greenhouses offer great challenges in design because of the need, on one hand, to allow radiation into the enclosed space for plant growth, and on the other hand also regulate temperature within the often tight limits that are compatible with the biology of the plants being grown.
Current greenhouse designs suffer from limitations in scale or expanse of coverage attributable mostly to the need for a construction frame to support the transparent cover and means for ventilation in the form of motorized fans and shutters. Another limitation to the scale of environment control is the economics that dictate heating the minimum volume of air necessary for plant growth. The small air volumes enclosed by current greenhouses provide little buffering against variations in external climatic factors such as radiation, temperature, wind and precipitation. This low buffering necessitates frequent cycling of climate control means to either remove excess heat by ventilation or to add heat by usually burning fossil fuels. To improve heating efficiency, insulation is usually provided in the form of an inflated air gap between either separate cover sheets or within discreet tubes disposed adjacent to one another to provide a modular, more or less air-tight cover. The double cover, wherein two layers of very large sheets are draped over the outside of the greenhouse frame, has been the main construction method. The apparatus is laborious to assemble and necessitates additional equipment for ventilation in the form of motorized fans and shutters. There has been a steady effort to improve inflatable greenhouses by providing an inflatable cover with variable openings between tubular modules as shown in U.S. Pat. No. 3,328,926 to Reinhard (1967), U.S. Pat. No. 4,027,437 to Monsky et al (1977). Attention to the practical application of this concept has been extended to inflatable insulation covers inside greenhouses as shown in U.S. Pat. No. 4,301,626 to Davis et al (1981), U.S. Pat. No. 4,290,242 to Gregory (1981), U.S. Pat. No. 6,000,170 to Davis (1999), U.S. Pat. No. 6,442,903 B1 to Hebert (2002). All the aforesaid designs are limited to small scale, mostly indoor applications mainly because of their dependency on a supporting frame and the lack of rugged integral means for module support. These designs also lack dependable means of maintaining openings between the tubes in windy outdoors conditions mostly because they utilize gravity-dependent mechanisms of tube deflation. Deflation of the tube per se does not automatically provide consistent gaps between modules because the tubes tend to flatten, sag and flap in the wind. The embodiment in U.S. Pat. No. 4,027,437 to Monsky et al (1977) achieves tube deflation by powered suction of air from the inflatable tube via ducting additional to that providing inflation air; whereas this dual plumbing system can inflate and deflate the device, consistent ventilation gaps between tubes are restricted to the side walls where spatially-offset tube assemblies part upon deflation. In fact, when the contiguous, oval tube arrangement disclosed in the aforesaid patent is deflated, a flattened ribbon-like curtain is created on the roof of the building mostly because the spacing between inflated tubes, center to center, is less than the tube maximum diameter, causing the flattened tubes to remain contiguous, if not overlapped. U.S. Pat. No. 3,328,926 to Reinhard (1967) does not disclose any reliable or consistent method of achieving ventilation gaps between inflatable tubes, upon deflation.
Therefore, it is an object and advantage of the Tensioned Inflatable Cover Module to provide a novel cover module suitable for outdoor use, fitted with integral support and dependable means of achieving ventilation gaps between adjacent modules. It is an object and advantage of the Tensioned Inflatable Cover Module to provide novel frame-less means of covering enclosed areas for environment control. It is also an object and advantage of the Tensioned Inflatable Cover Module to enable provision of enclosed spaces of unprecedented volume to afford improved buffering capacity against changes in external environmental factors. It is yet another object and advantage of this invention to exploit natural features such as canyons, craters, valleys, coulees, water bodies or man-made depressions to dispense of the need for construction frames. It is a further object and advantage of this invention to provide a novel variable cover that can also be used on framed building structures. Other objects and advantages of my invention will become apparent from the detailed description that follows and upon reference to the drawings.